I've been running my car which has Bridgestone RFs at the recommended tyre pressures (36psi front and 42psi rear) and I'm not that impressed. I just don't feel that the car is "planted" to the road and the ride quality is very hard (if I'm honest I'm disappointed with the car's handling in general). I know that the harsh ride is a feature of RFs but I didn't think that it would be as bad as it is. Has anybody tried reducing the pressure in the tyres and if so to what. I would normally play about with the pressures, but of course this might not make any difference because of the stiff walls which can support the weight of the car in the event of a puncture.
Tyre Pressures
- Thread starter Stafainn
- Start date
My E89 with 18" wheels/RFT and M Sport suspension is much better than my previous E85 Sport. I keep the front tyres at 2.5bar and rear at 3.0bar. I think the handling is also better, and it is just comfortable.
Did you have an E85/86 with RFT and sport suspension before?
Did you have an E85/86 with RFT and sport suspension before?
MikeS said:
'The answer to why are tyre pressures slowly increasing over the years, when comparing a like for like tyre appears to be simply that vehicle manufacturers want as high a tyre pressure as possible but without compromising the ride quality.These figures are obvious but they are the only figures quoted by BMW.
Braking from a speed of 90 km/h to 70 km/h on wet roads (identical vehicle):
- 40 metres with the tyre pressures set to 2 bar
- 44 metres with the tyre pressures set to 1 bar
When comparing an identical wheel and tyre combination on the same vehicle:
- The vehicle negotiated the corner at a maximum speed of 96 km/h with the tyre pressures set to 2 bar
- The vehicle negotiated the corner at a maximum speed of 87 km/h with the tyre pressures set to 1 bar
The advancements in tyre manufacture have allowed the vehicle manufacturers to increase the tyre pressures without having to compromise ride quality, in other words without having to make the tyres really stiff/hard. Obviously the material has to be much stronger to safely contain the higher tyre pressures but the experience gained with very early RFTs has allowed this to be achieved without a harsh/noisy ride.
I'll stick with the recommended pressures just now and see how I get on with them - thanks.
I've been driving front/mid engined rear wheel drive cars for the last 40 years, but this is my first Z4. It might be that I'm just not 100% used to it yet, so hopefully it'll grow on me when the better weather arrives.
Mike, it's just dawned on me that 1 bar is 14.5 psi and 2 bars is 29 psi. No wonder there is a marked improvement in performance - the tyre is virtually flat at 1 bar. Al in all that scenario doesn't really prove an awful lot in normal everyday driving conditions.
When I got mine, I found myself messing around with pressures and in the end I reduced all 4 corners to 32psi. The 36/42 set-up is way too harsh for me...
I actually haven't checked them for ages - a job for tomorrow!
I actually haven't checked them for ages - a job for tomorrow!
Indeed.. I'd be worried about running any tyre under-pressure, but especially RFT's as this would presumably cause rapid wear on the outer (harder) edges? (and perhaps an increase in heat meaning potential wall failure) While normal/highish pressures mean less comfort, they should in theory mean that all of the tyre surface is pressed against the road? At £300 a corner, I'm not keen to wear them quickly!
Had a puncture on my Bridgestone Run Flat this week... It took a lot of phone calls before anyone wd venture to repair it. They all said I wd need to buy a new tyre!!!Maniac said:
Anyway... the pressures shd have been 2.3 Front and 2.6 Rear but they were all down below 2.0!!!
So much for the Tyre Pressure warning system!
They were all new when I bought the car recently... Can't wait till they wear out and I can get some ordinary tyres fitted.
MikeS said:
sorry seem to have strayed into a new z4 thread.
doing about 1k per month - about 3k since had the car and haven't noticed anything unusual. I was more concerned about the ride, the rec' pressures made the car feel awful, tramling a nightmare.
i'm waiting for an excuse to replace with non-rfts.....
Reggie-g75, I am often confused by peoples' complaints about the RTF. I have no problem with them and certainly no tram-lining - in fact my 3 series on 'normal' tyres is far worse for tram-lining. I wonder how much of these comments are really just based on prejudice? 
I've joined club zed from a E60 520 SE, 17" RFTs and before that I've had 2.0 tdi audi A3,A4 & A6. When I drove it home I really did think WTF have I done. The drive was so incredibly hard and tramling was something I'd never felt before; it was quite unnerving to start with....
I have got used to it and am still contemplating a change to non-rfts, but £450 when I have 5.5mm left is something I'm not sure is the right thing to do. How much better can the ride be?
In any case, I ain't pumping them up.... :roll:
I have got used to it and am still contemplating a change to non-rfts, but £450 when I have 5.5mm left is something I'm not sure is the right thing to do. How much better can the ride be?
In any case, I ain't pumping them up.... :roll:
Martinmc666
Member
I was told by the dealer that the car has been setup to run with the run flats. Suspension and all so you should not replace with anything else. Was he just bullish**ing me ?
MUCH MUCH better!Reggie-g75 said:
Half Colin
Senior member
MUCH MUCH MUCH betterCoupeChief said:
